Needles conventionally used for percutaneous biopsies of hard tissue, particularly osteomedullary tissue, consist of a cylinder of varying length and diameter with a proximal end furnished with a handle and a distal end that is more tapered than the rest of the needle and ends in a hole with a sharp edge. Through the simultaneous pushing on and rotation of the needle on its axis in the tissue being biopsied, this end cuts out a cylinder that the needle takes into its cavity. Afterward, in order to extract this biopsy cylinder from the tissue it is necessary to interrupt the continuity of the distal end with the rest of the tissue penetrated by the needle. To accomplish this with conventional methods, the needle's handle is oscillated on a plane perpendicular to the needle's axis, with a pin at the point of entry of the tissue. This maneuver results in a break in the connections between the distal end of the biopsy and the remaining tissue at the level of the needle's distal end, which can then be extracted while keeping the biopsy away from the tapered end of the needle.
This method has the following disadvantages:
a) Often the biopsy is not kept away from the needle, either because it is not completely detached from the remaining tissue or because even a very slight depression is created inside the needle during tissue extraction and the biopsy aspiration that follows it, and the piece opposite from the tapered end of the needle cannot prevent this. This makes it necessary to repeat the entire process. PA1 b) Other times the situation described above results in the biopsy partially coming out from the distal end of the needle, leading to traumatization and breakage of the biopsy cylinder as it moves back through the tissue as well as loss of a part of the distal portion of the biopsy. PA1 c) The oscillation or oscillations performed on the needle in order to detach the biopsy always cause minimal breakage on the surface and in the hard tissue in which the needle is fixed. The width of this breakage slowly grows as the biopsy is pulled away from the surface of the tissue, with obvious suffering on the part of the patient and with changes in the needle's structure as it tends to bend and lose the necessary linearity.